Another way to sterilize digester effluent is to dilute with irrigation water and treat this mixture in shallow 30cm deep high rate algal ponding.
If you dont stir the ponds you will need a 30 day retention time in the pond. If you stir the ponds the retention time drops to 3 to 4 days. Stirring takes place with an eight fin paddle wheel powered with a mere 200 to 300 watt motor for a typical 500m2 algal raceway (4meter wide paddle wheel). In daylight periods of algal photosynthesis the digester effluent in the pond will become highly oxidized and the pH will elevate up to levels as high as pH11, effectively destroying pathogens and cracking viruses. 12 years of rigorous tests at EBRU in South Africa confirm this. Stirring encourages the growth of non-toxic algae as well as the creation of algal floccs that enable 70% of the algal biomass to be easily settled out using simple small settling pond. The nutrient rich oxidized effluent form the algal ponds can be used for irrigation or for aquaculture, creating a second cycle of nutrients in zooplankton and fish waste. Aquaculture waste is perfect for irrigation of aquaponic/hydroponic production of food. Algal biomass is an excellent fertilizer containing plant growth hormones. Also makes a good foliar feed when the cells are cracked open. Algal biomass also makes for good biogas production. And recent tests done by EBRU on the AD of algal biomass indicate a general improvement of about 10% in biogas production when algal biomass is codigested, as it seems that the algal biomass makes for healthy and happy AD bacteria. Mark _____ From: [email protected] [mailto:[email protected]] On Behalf Of Johan Carels Sent: 13 July 2011 09:55 PM To: [email protected] Subject: [Digestion] pathogens which might create a health hazard Dear Johan, Regarding pathogens which might create a health hazard. There are reports on pathogens for man, animal, and plant, which might survive the biogas process. As the input material of any biogas plant which is not operated on a farm level may contain many different types of pathogens you may accumulate these germs even if they are in a low number in the digestate. Suggest to pasturise ( heating at 70°C during 60 minutes) all the digestate since you hav e this heat available from the cogenerater [cooling water, turbocooling, exhaust gase-heat]. This will kill all pathogens. K rgds Johan Carels www.jcarels.be No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.901 / Virus Database: 271.1.1/3762 - Release Date: 07/13/11 08:34:00
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